1. Field of the Invention
The present invention is in the field of gas analysis and more specifically relates to an improvement in gas sample chambers that are used in non-dispersive infrared gas analyzers.
2. The Prior Art
In Japanese Publication (Kokai) No. 59-173734(A) Miyazaki describes a tubular gas sample chamber having the shape of a corkscrew, having a source of radiation at one end and a detector of radiation at the other end. Gas is pumped through the gas sample chamber.
A diffusion-type gas sample chamber is shown and described in U.S. Pat. No. 5,163,332 for GAS SAMPLE CHAMBER by the present inventor. In that invention, the gas to be analyzed is permitted to diffuse into and out of the sample chamber through semipermeable membranes that cover apertures in the wall of the chamber.
An improved diffusion-type gas sample chamber is described in U.S. application Ser. No. 07/915,003 filed Jul. 16, 1992 for "Improved Diffusion-Type Gas Sample Chamber", by the present inventor. The improvement is obtained by locating both the source of radiation and the detector at one end of the chamber and by providing a specularly reflective surface perpendicular to the axis of the chamber at its other end. This arrangement effectively doubles the length of the chamber.
The present invention effects a still further improvement in gas sample chambers and can be used in pumped chambers, diffusion-type chambers, and in chambers that are folded by use of a specular reflector.